选取指定(p)父元素下的第一个子元素(无关目标元素在父元素中所处的位置):
实例:
<!DOCTYPE html>
<html lang='zh-cn'>
<head>
<title>Insert you title</title>
<meta http-equiv='description' content='this is my page'>
<meta http-equiv='keywords' content='keyword1,keyword2,keyword3'>
<meta http-equiv='Content-Type' content='text/html; charset=utf-8'>
<script type='text/javascript' src='./js/jquery-1.12.1.min.js'></script>
<style type='text/css' >
*{margin:0;padding:0;} html{font:400 15px/1.2em 'Courier New';color:#666;}
div > *{margin:10px 0;cursor:pointer;} #demo{width:750px;margin:75px auto;} button{padding:5px 15px;border:0;outline:none;margin-top:-5px;border-radius:2px;font:400 12px/1.2em 'Courier New';}
.active{background-color:yellow;transition: .3s;} .hover{background-color:red;transition: .3s} p{text-indent:8px;} </style>
<script type='text/javascript'>
/** 概述 选取指定(p)父元素下的第一个子元素(无关目标元素在父元素中所处的位置) */ $(function(){ $('p:first-of-type').addClass('active'); }); </script>
</head>
<body>
<div id='demo'>
<ul id='list'>
<li>The first paragraph in div.</li>
<li>The first paragraph in div.</li>
<li>The first paragraph in div.</li>
<li>The first paragraph in div.</li>
<li>The first paragraph in div.</li>
</ul>
<p class='test'>The first paragraph in div.</p>
<div style='border:1px solid #3695BC'>
<p>The first paragraph in div.</p>
</div>
<div style='border:1px solid #3695BC'>
<p>The first paragraph in another div.2</p>
<p>The last paragraph in another div.2</p>
</div>
<div>
<p>The first paragraph in div.</p>
</div>
<div style='border:1px solid #3695BC'>
<span style='white-space: pre-wrap;'> The first span in div.</span>
<p>The first paragraph in div.</p>
<span style='white-space: pre-wrap;'> The first span in div.</span>
</div>
</div>
</body>
</html>